No Sound on Internet

Hello,

I am having issues with my Internet sound. The sound seems to be disabled, but I can still hear sound when I do sound checks, play my iTunes/FrostWire etc. The only time it fails to work is on Internet videos. I've checked my tools:internet options: enable sound on web videos, and I've attempted to fix my firewall by allowing third parties but nothing seems to work. Any suggestions? I'm EXTREMELY frustrated! Thank you!